// Licensed to the Apache Software Foundation (ASF) under one
// or more contributor license agreements.  See the NOTICE file
// distributed with this work for additional information
// regarding copyright ownership.  The ASF licenses this file
// to you under the Apache License, Version 2.0 (the
// "License"); you may not use this file except in compliance
// with the License.  You may obtain a copy of the License at
//
//   http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing,
// software distributed under the License is distributed on an
// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.  See the License for the
// specific language governing permissions and limitations
// under the License.

package org.apache.doris.common.util;

import org.apache.doris.common.Pair;

import com.github.benmanes.caffeine.cache.CacheLoader;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Maps;
import com.google.common.collect.Streams;

import java.util.List;
import java.util.Map;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;
import java.util.stream.Collectors;

public abstract class CacheBulkLoader<K, V> implements CacheLoader<K, V> {

    protected abstract ExecutorService getExecutor();

    @Override
    public Map<K, V> loadAll(Iterable<? extends K> keys)
                throws ExecutionException, InterruptedException {
        List<Pair<? extends K, Future<V>>> pList = Streams.stream(keys)
                .map(key -> Pair.of(key, getExecutor().submit(() -> load(key))))
                .collect(Collectors.toList());

        Map<K, V> vMap = Maps.newLinkedHashMap();
        for (Pair<? extends K, Future<V>> p : pList) {
            vMap.put(p.first, p.second.get());
        }
        return ImmutableMap.copyOf(vMap);
    }
}
